What do you want?
I've looked at several of the old Cherubini 27s and haven't seen one with a holding tank (probably for a good reason). Most were equipped with porta potties and some with an external discharge (now illegal). I’d give this some serious thought. Dealing with a marine sanitation system can be a real pain. The porta potties are the simplest and easiest to keep “odor free”. There is the issue of having to empty the darn thing, which at best, is a hike to the marina’s bathroom facility. At worst, as in my case, the marina prohibits the dumping of porta potties and insists that they be pumped out at the pump out station….for $5.00! (This struck me as a little unfair, charging the same $5.00 to me as they would the guy with the big cruiser with a 40 gal holding tank). I always said when I grow up and get a bigger boat I’m going to have a real marine sanitation system. Now that I have one, I long for the simple days with the porta potty! If you are a weekender like me, you will only “generate” 3 or 4 gal of waste (including flush water), and if you skip a weekend for whatever reason, you could theoretically have waste sitting in your tank for 5 to six weeks (assuming at least a 20 gal tank)…..in the hot summer….get the picture? With this type of usage, most systems will be prone to have odor problems. Again, give this some thought before you take the plunge.